Limits...
A universal scaling relationship between body mass and proximal limb bone dimensions in quadrupedal terrestrial tetrapods.

Campione NE, Evans DC - BMC Biol. (2012)

Bottom Line: Therefore, accurate and consistent body mass estimates are essential for inferring numerous aspects of paleobiology in extinct taxa, and investigating large-scale evolutionary and ecological patterns in the history of life.Significant differences in the limb scaling of mammals and reptiles are noted in comparisons of limb proportions and limb length to body mass.The conserved nature of the relationship between stylopodial circumference and body mass suggests that the minimum diaphyseal circumference of the major weight-bearing bones is only weakly influenced by the varied forces exerted on the limbs (that is, compression or torsion) and most strongly related to the mass of the animal.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2. nicolas.campione@mail.utoronto.ca

ABSTRACT

Background: Body size is intimately related to the physiology and ecology of an organism. Therefore, accurate and consistent body mass estimates are essential for inferring numerous aspects of paleobiology in extinct taxa, and investigating large-scale evolutionary and ecological patterns in the history of life. Scaling relationships between skeletal measurements and body mass in birds and mammals are commonly used to predict body mass in extinct members of these crown clades, but the applicability of these models for predicting mass in more distantly related stem taxa, such as non-avian dinosaurs and non-mammalian synapsids, has been criticized on biomechanical grounds. Here we test the major criticisms of scaling methods for estimating body mass using an extensive dataset of mammalian and non-avian reptilian species derived from individual skeletons with live weights.

Results: Significant differences in the limb scaling of mammals and reptiles are noted in comparisons of limb proportions and limb length to body mass. Remarkably, however, the relationship between proximal (stylopodial) limb bone circumference and body mass is highly conserved in extant terrestrial mammals and reptiles, in spite of their disparate limb postures, gaits, and phylogenetic histories. As a result, we are able to conclusively reject the main criticisms of scaling methods that question the applicability of a universal scaling equation for estimating body mass in distantly related taxa.

Conclusions: The conserved nature of the relationship between stylopodial circumference and body mass suggests that the minimum diaphyseal circumference of the major weight-bearing bones is only weakly influenced by the varied forces exerted on the limbs (that is, compression or torsion) and most strongly related to the mass of the animal. Our results, therefore, provide a much-needed, robust, phylogenetically corrected framework for accurate and consistent estimation of body mass in extinct terrestrial quadrupeds, which is important for a wide range of paleobiological studies (including growth rates, metabolism, and energetics) and meta-analyses of body size evolution.

Show MeSH

Related in: MedlinePlus

Limb scaling patterns in mammalian clades. Lines are fitted based on the SMA results presented in Table 1. (A) Log femoral length and circumference plotted against log body mass. (B) Log humeral length and circumference against log body mass. (C) Log femoral length plotted against log humeral length. (D) The log of combined humeral and femoral circumference against log body mass. SMA, standardized major axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3403949&req=5

Figure 1: Limb scaling patterns in mammalian clades. Lines are fitted based on the SMA results presented in Table 1. (A) Log femoral length and circumference plotted against log body mass. (B) Log humeral length and circumference against log body mass. (C) Log femoral length plotted against log humeral length. (D) The log of combined humeral and femoral circumference against log body mass. SMA, standardized major axis.

Mentions: Results from the standardized major axis (SMA) analyses comparing clades based on the raw non-phylogenetically corrected data are provided in Figures 1 and 2, and Table 1; comparisons are summarized in Tables 2 and 3. Size class comparisons are presented in Figure 3 and Tables 4 and 5. All analyses show strong correlations with each other, and to body mass (that is, size) as indicated by a mean coefficient of determination of 0.9446 ± 0.0093 for the clade comparisons, and 0.914 ± 0.014 for comparisons between size classes.


A universal scaling relationship between body mass and proximal limb bone dimensions in quadrupedal terrestrial tetrapods.

Campione NE, Evans DC - BMC Biol. (2012)

Limb scaling patterns in mammalian clades. Lines are fitted based on the SMA results presented in Table 1. (A) Log femoral length and circumference plotted against log body mass. (B) Log humeral length and circumference against log body mass. (C) Log femoral length plotted against log humeral length. (D) The log of combined humeral and femoral circumference against log body mass. SMA, standardized major axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3403949&req=5

Figure 1: Limb scaling patterns in mammalian clades. Lines are fitted based on the SMA results presented in Table 1. (A) Log femoral length and circumference plotted against log body mass. (B) Log humeral length and circumference against log body mass. (C) Log femoral length plotted against log humeral length. (D) The log of combined humeral and femoral circumference against log body mass. SMA, standardized major axis.
Mentions: Results from the standardized major axis (SMA) analyses comparing clades based on the raw non-phylogenetically corrected data are provided in Figures 1 and 2, and Table 1; comparisons are summarized in Tables 2 and 3. Size class comparisons are presented in Figure 3 and Tables 4 and 5. All analyses show strong correlations with each other, and to body mass (that is, size) as indicated by a mean coefficient of determination of 0.9446 ± 0.0093 for the clade comparisons, and 0.914 ± 0.014 for comparisons between size classes.

Bottom Line: Therefore, accurate and consistent body mass estimates are essential for inferring numerous aspects of paleobiology in extinct taxa, and investigating large-scale evolutionary and ecological patterns in the history of life.Significant differences in the limb scaling of mammals and reptiles are noted in comparisons of limb proportions and limb length to body mass.The conserved nature of the relationship between stylopodial circumference and body mass suggests that the minimum diaphyseal circumference of the major weight-bearing bones is only weakly influenced by the varied forces exerted on the limbs (that is, compression or torsion) and most strongly related to the mass of the animal.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2. nicolas.campione@mail.utoronto.ca

ABSTRACT

Background: Body size is intimately related to the physiology and ecology of an organism. Therefore, accurate and consistent body mass estimates are essential for inferring numerous aspects of paleobiology in extinct taxa, and investigating large-scale evolutionary and ecological patterns in the history of life. Scaling relationships between skeletal measurements and body mass in birds and mammals are commonly used to predict body mass in extinct members of these crown clades, but the applicability of these models for predicting mass in more distantly related stem taxa, such as non-avian dinosaurs and non-mammalian synapsids, has been criticized on biomechanical grounds. Here we test the major criticisms of scaling methods for estimating body mass using an extensive dataset of mammalian and non-avian reptilian species derived from individual skeletons with live weights.

Results: Significant differences in the limb scaling of mammals and reptiles are noted in comparisons of limb proportions and limb length to body mass. Remarkably, however, the relationship between proximal (stylopodial) limb bone circumference and body mass is highly conserved in extant terrestrial mammals and reptiles, in spite of their disparate limb postures, gaits, and phylogenetic histories. As a result, we are able to conclusively reject the main criticisms of scaling methods that question the applicability of a universal scaling equation for estimating body mass in distantly related taxa.

Conclusions: The conserved nature of the relationship between stylopodial circumference and body mass suggests that the minimum diaphyseal circumference of the major weight-bearing bones is only weakly influenced by the varied forces exerted on the limbs (that is, compression or torsion) and most strongly related to the mass of the animal. Our results, therefore, provide a much-needed, robust, phylogenetically corrected framework for accurate and consistent estimation of body mass in extinct terrestrial quadrupeds, which is important for a wide range of paleobiological studies (including growth rates, metabolism, and energetics) and meta-analyses of body size evolution.

Show MeSH
Related in: MedlinePlus